Methods, apparatus, and product for distributed garbage collection

Abstract

In accordance with the present invention a process is provided for allocating and deallocating resources in a distributed processing system having a requester platform and a server platform. The process involves receiving a request from the requestor platform referring to a system resource and specifying a requested lease period, permitting shared access to the system resource for a lease period, sending a return call to the requestor platform advising of the lease period, and deallocating the system resource when the lease period expires.

What is claimed is:  
     
       1. A method for managing objects performed by at least one processor comprising: 
       sending a request to access an object, including a reference corresponding to the object and indicating a period of time for which access to the object is requested;  
       receiving a response to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted;  
       determining whether the period for which access to the object has been permitted is about to expire; and  
       providing a notification that the period for which access to the object has been permitted is about to expire.  
     
     
       2. The method of claim  1 , further comprising: 
       renewing the request to access the resource based upon a determination that access to the resource is required.  
     
     
       3. The method of claim  1 , wherein the receiving step includes: 
       incrementing a counter corresponding to the object reflecting the response.  
     
     
       4. The method of claim  1 , further comprising: 
       sending a notification indicating that access to the object is no longer required.  
     
     
       5. The method of claim  4 , wherein sending a notification indicating that access to the object is no longer required, includes: 
       decrementing a counter corresponding to the object reflecting the notification.  
     
     
       6. The method of claim  5 , wherein decrementing a counter corresponding to the object reflecting the notification, includes: 
       invoking a process to collect resources corresponding to the object upon a determination that the counter corresponding to the object indicates that access to this object is no longer required.  
     
     
       7. A method for managing resources comprising the steps, performed by at least one processor, of: 
       permitting access to a resource for a particular time interval in response to a set of requests for access to the resource;  
       incrementing a reference count corresponding to the resource, the reference count indicating a number of processes currently having access to the resource; and  
       releasing the resource when the time interval expires.  
     
     
       8. The method of claim  7 , wherein the permitting operation includes 
       determining the time interval based on at least one of a requested lease period, a measure of the resource, and granted lease periods for the resource.  
     
     
       9. The method of claim  7 , wherein the releasing operation includes reclaiming the resource when access to the resource is no longer requested. 
     
     
       10. The method of claim  7 , wherein the releasing operation includes 
       reclaiming the resource when the reference count indicates no processes currently access the identified resource.  
     
     
       11. The method of claim  7 , wherein the permitting operation includes 
       guaranteeing integrity of the resource for the time interval.  
     
     
       12. A method for managing objects in a distributed system having a client computer and a server computer, the method comprising: 
       performing, by the client computer, the steps of:  
       sending a request to the server computer to access an object, including a reference corresponding to the object and indicating a period of time for which access to the object is requested,  
       receiving a response from the server computer to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted,  
       determining whether the period for which access to the object has been permitted is about to expire, and  
       renewing the request to access the resource based upon a determination that access to the resource is required; and  
       performing, by the server computer, the steps of:  
       receiving the request from the client computer to access the object,  
       sending the response to the request,  
       determining whether the period for which access to the object has beer permitted has expired, and  
       collecting a resource corresponding to the object based on the determination.  
     
     
       13. A method for managing objects performed by at least one processor comprising: 
       sending a request to access an object, including a reference corresponding to the object and indicating a period of time for which access to the object is requested;  
       receiving a response to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted; and  
       reclaiming a resource associated with the object when access to the object is no longer required.  
     
     
       14. The method of claim  13 , wherein reclaiming a resource further includes decrementing a reference counter, the reference counter counting a number of processes currently having access to the object. 
     
     
       15. A system for managing objects, comprising: 
       a client computer for sending a request to access an object, wherein the request includes a reference corresponding to the object and indicating a period of time for which access to the object is requested; and  
       a server computer for receiving the request to access the object from the client computer, generating a response to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted, determining whether the period of time for which access to the object has been permitted is expired and collecting a resource corresponding to the object in response to determining that the period of time for which access to the object is permitted has expired.  
     
     
       16. The system of claim  15 , wherein the server computer includes a counter for indicating whether or not access to the object is required, and wherein the counter is incremented when the client computer is granted access to the object, and the counter is decremented when a notification is received from the client computer that access to the object is no longer required.